Biologic therapies in
rheumatoid arthritis are now part of standard practice for disease that proves difficult to control with conventional disease-modifying
anti-rheumatic drugs. While anti-
tumor necrosis factor therapies have been commonly used, other targeted
biologic therapies with different mechanisms of action are becoming increasingly available.
Abatacept is a recombinant fusion protein that inhibits the T-cell costimulatory molecules required for T-cell activation. Intravenous
abatacept has good clinical efficacy with an acceptably low toxicity profile in
rheumatoid arthritis, but the subcutaneous mode of delivery has only recently become available. In this article, we examine key efficacy and safety data for subcutaneous
abatacept in
rheumatoid arthritis, incorporating evidence from five large Phase III studies that included people with an inadequate response to
methotrexate and an inadequate response to biologic disease-modifying
anti-rheumatic drugs. The results demonstrate that subcutaneous
abatacept has efficacy and safety comparable with that of intravenous
abatacept and
adalimumab. In addition, inhibition of radiographic progression at year 1 in relatively early
rheumatoid arthritis is consistent with that of
adalimumab. Subcutaneous
abatacept is well tolerated, with very low rates of discontinuation in both short-term and long-term follow-up.